Soils Flashcards
Loam soil consists of
the mineral fraction, organics, water and air.
The mineral fraction of soil consists of
sand, silt & clay.
Soil texture is determined by
the relative proportions of sand, silt & clay.
Clay holds on to water because
clay has an overall negative electrical charge while water has an overall positive charge.
Clay holds on to chemical salts because
clay has an overall negative electrical charge while most salts have overall positive charges.
What do salts do to the structure of clay?
They disperse them, which disrupts the structure of clay.
What does adsorbed calcium do to the structure of clay?
It causes the clay particles to “flocculate” which improves the structure.
Organic matter aggregates to soil particles which has what effect on the soil?
It allows easier movement of air, water and plant roots within the soil.
What are 2 primary purpose of soil in gardens or agriculture?
First to physically support plants (the root system) and second, to act a reservoirs for water, oxygen, and nutrients needed by plants.
Why is the pore space of dirt important to plants?
Pore space is important to convey water and nutrients, circulate air and other gases, and provide space for the roots to grow.
What are the components (& percentages) of “textbook” soil?
45% mineral matter, 25% air, 25% water & 5% organic matter.
What is the average percentage of organic matter in Utah soils?
Less than 1%.
What is hardpan?
A very dense or hard layer that occurs in some soils. Water accumulates above the hardpan but cannot soak through it.
Define Field Capacity.
The moisture content of a recently irrigated soil after the gravitational water drains away is said to be at field capacity. A soil at field capacity holds the most water it can hold despite gravity.
